Thin HTS film of a YBCO with the frozen strains

Strained HTS YBa2CuO7-delta films of thickness more than the critical one were deposited on LaAlO3 substrates (100) by the laser ablation method. Strains were frozen in the films by rapid cooling just after the laser deposition. These films, which we call the frozen-strain films, have a very surprising temperature dependence of critical current density: it has a characteristic minimum in the temperature range of 55-57 K. The critical current density at 77 K is suppressed from 10(6) A/cm2 down to 10 A/cm2 at 77 K and below, but these films are very stable at thermocycling from 300 K to the nitrogen boiling temperature. The scanning tunnel microscope study suggests that strained domains are formed in these films. The domain sizes reduce with increasing strains and average between land 2.4 gm. Magnetic field penetration into the frozen-strain films differs from mono and granular films. This also suggests the macroscopic structurisation of the frozen-strain films.